esset

I have this wierd issue with my z06 (2015 w/ z07 package) that happened today and I'm not sure if I'm the issue or the car :P

I turn the car on. Drive it for a while to let the engine heat up. Turn up on the highway and floor it (I'm in TRACK MODE, Sport 1) and as soon as I hit 250km/h (~155mph) the "Reduce engine power" feature sets in. Is this normal behavior? Can my car be top speed reduced?? My car was sold on the Swedish market.

It's not a temperature issue like overheating, I had that last year and that gave a different message in the display. This one clearly just says "Reduced engine power" and then just sets the car in "stealth mode" or what you want to call it.

I tired looking in the manual to see if the TRACK MODE has some sort of top speed limiter but I can't see anything about that. I mean the car should be able to hit 180mph easily.

Thank you

Snorman

Never heard of it. That's the message that appeared on the DIC?
S.

esset

Yeah right on the DIC and the HUD. I tried the car in SPORT MODE as well and same behavior, as soon as I hit 155mph the reduced engine power message appeared.

I only had ~20-25% gas left in the tank. Could that be something?

I had to completely turn the car off to get it out of stealth mode and return to "normal behavior".

Snorman

Are there speed limits on export cars? I thought most of the European cars were limited by those manufacturers.
S.

wstaab

Many cars in Europe have a speed limiter set at 155 mph for certain models.
BMW and Mercedes are two. Check with GM Europe and see if it was a requirement for cars sold in your country. US spec cars have a speed limiter of 204 mph.
We also do not have headlight washers in the US which are required in Europe.

esset

Okay I will have to ask the dealership then. Do you guys think this is something they can lift in the ECU or are the rules strict about these things?

Its wierd though that it shuts the car down when hitting the limiter. Shouldn't it just keep the car from going forward? Shutting down seems like a wierd behavior for a top speed limiter.

Really sad to have a car capable of all these things but always coming up short. I love this car to death.

Bill Dearborn

What do you mean by Stealth Mode? The engine sound management permits the owner/driver to set the exhaust in Stealth Mode so the car is quiet but that doesn't have anything to do with reduced power.

I suspect that if you hit some sort of a speed limiter forced by government regulations you wouldn't see a reduced power message. You would just feel the car stop accelerating just like you do when the engine hits the rev limiter.

By the way there are some people in the US that are hitting 160+ on tracks so it isn't something that affects all cars.

Bill

esset

Yeah sorry "stealth mode" wasn't really the right description. What I mean was that the car goes into "limp mode" (if that makes any more sense :P) when it reduces power and shuts parts of the engine of. That is whats happening here.

At 155mph the "Reduced engine power" message appears and the car goes limp.

As you say if its a top speed limitier shouldn't it just stay as is but not keep on going - it shouldn't reduce power like it does now.

Really strange indeed....

NSC5

From page 124 of the U.S. manual (pdf copy, may be different in your country) the following appears:

"Engine Power Messages
ENGINE POWER IS REDUCED
This message displays when the
vehicle's engine power is reduced.
Reduced engine power can affect
the vehicle's ability to accelerate.
If this message is on, but there is no
reduction in performance, proceed
to your destination. The
performance may be reduced the
next time the vehicle is driven. The
vehicle may be driven at a reduced
speed while this message is on, but
maximum acceleration and speed
may be reduced. Anytime this
message stays on, the vehicle
should be taken to your dealer."

On Edit, I wouldn't be surprised if there is a fuel delivery issue. If the fuel rail pressure is below the commanded rail pressure then power will be reduced to avoid a lean condition which can be quickly destructive to your engine.

Dabigsnake

I feel your pain. Sure wish GM could give us the details of things they want(or set) the engine to do at certain parameters. When mine was new with only 600 miles on it, the first time I tightened it up, it went "boom" and shut down to a serious limited power, with check engine light on. I limped into a station, and restarted it a few times and then it cleared. Now I get reduced power on the track without any messages displayed. I bought a dash logic to be able to see what it is doing. Knock retard? fuel trims? ??

I want GM to tell me.....hey, with your coolant temp of ?? and your intake air temp at ?? and running 93 octane....you will experience diminished performance because we back the timing up ??? but don't tell you chitz on the DIC. Why can't they have a code come up on the dash that we could then relate to what is happening. Having the dealer scan it afterwards helps, but?

Don't really want to get a tune and void the warranty, but sure would like it to run at peak performance for at least 2 laps. Is that too much to ask?

dar02081961

Sometimes if you press the ONSTAR button shortly after one of these incidents they will/can tell you what the issue is/was. It is a crap shoot and depends on the person on the other end of the line as to how much or how little info you get.

This why it is good to have an inexpensive scanner to pull the codes. At least then you will know what shut you down.

dar02081961

As a few have said earlier this is what happens when the car hits the speed limiter. Yours is obviously set at 155 mph. This is exactly what a friends did after he had a tune applied. Except his was set at 135 mph. It gave the same messages and responded the same as yours did at 155 mph.

Your dealer or GM rep should be able to verify where the speed limiter is set for cars sold in your country. Regardless there are solutions out there if you really want to go there.

Alysha

I had the exact same issue. Turned out to be a fuel sensor problem. Dealership said several had the same issue as mine.

esset

Thank you. Very helpfull information Alysha. So after this you can now max the cars top speed without it shutting down?

Thanks for the info. So you mean that GM and my dealership should be able to lift the limit for me or do I have to do this myself through some tuner company?

dar02081961

I am not sure what GM's policy is for your country. If they were forced to put the limiter their by some regulation I am sure they wont remove it. If it was just a gentlemen's agreement between all manufactures to limit all cars to 155 mph they may remove it if they have that capability.

Regardless most any reputable tuning software can remove it.
Or you could have a tuner in your area remove it as well.
Of course then there is the whole discussion about voiding the warranty and so forth. Bunch of threads here on that subject

I will add because your issue actually happened at 155 mph I doubt it is a mechanical problem. 155 mph has been an agreed upon limit for some cars in Europe for years. (not for Vettes though)
So I am thinking it would be one hell of a coincidence for a mechanical problem to just happen to occur at that exact speed.

And here is a bonus for the gallery.....most normal spec Z06's are limited by the tune to 203 mph. I believe they are capable of a wee bit more.

mcoomer

Silly question, but have you taken your car to the dealer yet? If not, why not?

Based on your initial description of the problem, and the added information by NSC5 and Alysha, it would appear that your car is broken. In your initial post, you said that the "Reduced Engine Power" feature set in when you hit ~155mph. From the information that NSC5 found in the manual, this is not a feature but a message saying that the car detected a problem and to protect itself it is reducing power from the engine. Alysha went further to say that she experienced the same problem and the dealer made repairs to her fuel system.

You need to get your car in for service. While it's there you can ask them about the presence of a speed limiter, but if GM put one in place I'd be stunned if the dealer is authorized to remove it. Still, you'll get your car fixed and question answered.

Mike

NSC5

In one post the OP states he has to completely turn off the car to get it to resume normal power. I have never seen any other vehicle with a maximum speed limiter that works in that fashion-in other vehicles behavior returns to normal once you drop below the limited speed.

As Mike summarized, get it to the dealer.

esset

POST UPDATE!

My car has now been to the dealer and here are the results of everything

1. The car does NOT have a speed limiter (European model)

2. The issue why the car was shuting the engine down was (to a 90% certainty) that the radiator had a small small chip in the front which made some fluid leak out. The car computer probably sensed by some temperature sensor that something wasn't right when hitting higher speeds so for safety shut the engine off. Once we swapped in a new stock radiator (front) everything was fine and car could hit 280km/h without any issues.

Thanks everyone for the help!

coladin

Don't you wish we could talk about the same problems like the Europeans? I'm in jail top of 2nd...

Z06Norway

Did 201 mph on German Autobahn last month and couldn't feel any power degradation .... on track is another story